Abstract

In this thesis we study the motion of a 2D single, solid particle suspended in a viscoelastic fluid. We perform simulations by means of a finite elements method method. An ALE particle mover is combined with a DEVSS-G/SUPG formulation together with a log-representation of the conformation tensor, in order to easily manage the particle motion and significantly improve numerical convergence at finite Deborah numbers. Finally, the rigid-body motion on the particle boundary is imposed through Lagrange multipliers. First we will show that the particle moves towards a wall if immersed in a non-Newtonian fluid under continuous shear flow, in qualitative agreement with experimental findings. Anyway most of the experiments are performed under oscillatory shear flow, so we will study the effect of oscillation on the migration of the particle and we will compare our results with experimental data. Finally we will report results of migration when particle is moving between two concentric rotating cylinders. We will show that the migration is strongly affected by the curvature of the two cylinders. We will also show the effect of the suspending fluid and the particle size.